Fredericksburg.com - Theologian contends married couples shouldn't go childless

Now this is an article from a secular press. But is Albert Mohler really using only Psalm 127:3-5, where it talks about children as a gift from God being a proof text that we "must" have children? C'mon, he's not serious. The article says he's a theologian — must not be in hermeneutics. Is there any place else in Scripture this argument could be made? I can't think of one. Now certainly I'm doing my part with 4 kids of my own but I never felt I was sinning against God if I didn't.